Microwave ovens heat material with microwave radiation which electrostatically changes the orientation of polar molecules in the material. Microwave heating is very rapid because the microwave radiation goes directly to the molecular structure of the material. This is accomplished without introduction of any heating element into the material. It is also done without passing electrical current through the material for resistive heating.
Heating with microwave radiation is advantageous over other techniques, such as baking, broiling, or boiling, because the material is heated without the container being heated to temperatures in excess of the material. As a result, a wide variety of containers which do not tolerate high temperatures may be used to hold materials during microwave heating.
Despite the desirable features, microwave ovens suffer from several practical problems. A principal problem is that the microwave oven occupies a substantial space which cannot conveniently be recovered for other uses. For example, a portable microwave oven may consume a substantial portion of a kitchen countertop. Microwave ovens are typically too heavy and bulky to be removed easily from the countertop when the additional countertop space is desired.
One prior approach to the space problem was to mount the microwave oven in kitchen cabinetry, such as below an upper set of cabinets. Another approach uses an exhaust hood and microwave combination which mounts above a conventional electric stove. Although each of these approaches remove the microwave oven from the countertop, they merely relocate the microwave oven to another kitchen space. Accordingly, a large volume of kitchen space is still dedicated to the microwave oven.
Another problem experienced by prior microwave ovens is the lack of user accessibility to the material being heated in the oven. For example, the user must typically remove the container from the microwave oven to stir the contents. Removal is also typically needed to determine whether the contents are sufficiently cooked or heated. The user must then replace the container to complete the cooking process.
A third problem facing prior microwave ovens is the relative difficulty of cleaning the oven interior. Portions of the microwave ovens, such as microwave stirrers, rotating tables, and air-flow holes in the oven surface, provide irregular surfaces which are commonly exposed to accidental spills. Unfortunately, these areas are difficult to clean.
Microwave cooking appliances built according to the present invention provide the benefits of microwave heating while eliminating or minimizing the practical drawbacks concerning occupation of counter space, limited accessibility to the material being heated, and difficulty in cleaning interior surfaces of the appliance.